[phenixbb] restraining covalent links between symmetry related molecules

Dear all, I am attempting to add a bond restraint that connects a serine in one molecule to a carbon located in its symmetry mate in the adjacent unit cell. Atom selection 1: chain 'A' and resid ' 230 ' and name ' C ' and altloc 'A' Atom selection 2: chain 'A' and resid ' 179 ' and name ' OG ' and altloc 'A' and (*insert symmetry keyword here*) 'x-1,y,z' (altloc B in both cases is not covalently attached) I cannot seem to find a complete description of the atom selection syntax in the Phenix documentation to specify which symmetry mate. and the gui/ phenix graphics does not have any way to generate symmetry mates. What is the keyword that specifies a symmetry mate? Thanks, Dave Lodowski